Nanocomposites to monitor wind turbine blade structure

Gary D. Seidel, assistant professor of aerospace engineering in the College of Engineering atVirginia Tech developed a carbon nanotube-enhanced composite for structural health monitoring sensors to improve the resiliency of huge wind turbine blades.

Wind turbine blades enjoy a steady wind but can be damaged by gust-induced vibrations. Seidel proposes to create tiny sensor patches that can be selectively placed in key locations where it is anticipated that damage will start. The patches are made of the same base material as the blade but sprinkled with carbon nanotubes, resulting in a nanocomposite sensor which adds negligible weight to the structure.

The submicroscopic carbon nanotubes can be highly conductive, like invisible, extremely lightweight, electrical wires. Placing the highly conducting carbon nanotubes inside a polymer material makes the resulting nanocomposite patch's conductivity sensitive to deformation. As the material is deformed by a stress on the blade, the nanotubes shift, move closer together, and their conductivity jumps – one mechanism behind the phenomenon known as a piezoresistive response. The change in the nanocomposite conductivity sends a signal to the wind turbine control center, allowing the operator to then know which blade is stressed and should be turned off to prevent further damage to that turbine.

Seidel's focus is on assessing the sensing capabilities of the nanocomposite and building multiscale models for use in structural health monitoring software algorithms. His preliminary models have demonstrated that he can create nanocomposites that respond to stresses with conductivity changes.

Based on the mechanism behind the piezoresistive response of our nanocomposites, necessary tools will be created for nanocomposite sensor development and tailoring for the wind turbine blade application.

DNA Could Lead to Enhanced Electronics

Nanoscience has the potential to play an enormous role in enhancing a range of products, including sensors, photovoltaics and consumer electronics. Scientists in this field have created a multitude of nano scale materials, such as metal nanocrystals, carbon nanotubes and semiconducting nanowires. However, despite their appeal, it has remained an astounding challenge to engineer the orientation and placement of these materials into the desired device architectures that are reproducible in high yields and at low costs.

Jen Cha, a UC San Diego nanoengineering professor, and her team of researchers, have discovered that one way to bridge this gap is to use biomolecules, such as DNA and proteins.

Self-assembled structures are often too small and affordable lithographic patterns are too large. But rationally designed synthetic DNA nanostructures can access length scales between 5 and 100 nanometers and bridge the two systems.

People have created a huge variety of unique and functional nanostructures, but for some intended applications they are worthless unless billions or trillions of individual structures can be placed at the same time, at precise locations. This research can lead researchers to a step closer to solving this very difficult problem.

This work is the first example of how top down lithography can be merged with bottom up self assembly approach to build arrays. That signifies that substrate is patterned by conventional lithography merge it with something that can direct the assembly of even smaller objects, such as those having dimensions between 2 and 20 nanometers. There is a need an intermediate template. For that DNA origami is there which has the ability to bind to something else much smaller and direct their assembly into the desired configuration; there by transistors can be built from carbon nanotubes.

For the last 6years, Cha's research has focused on using biology to engineer the assembly of nanoscale materials for applications in medicine, electronics and energy. One of the limitations of nanoscience is it doesn't allow mass production of products, but Cha's work is focused on trying out how to do that and do it cheaply. Much of her recent work has focused on using DNA to build 2D structures.

Nanobiotechnology Product Market Size

The total market for nanobiotechnology products is $19.3 billion in 2010 and is growing at a compound annual growth rate (CAGR) of 9% to reach a forecast market size of $29.7 billion by 2015.

Medical applications, including drug delivery and microbicides, dominate today’s market, with sales of $19.1 billion in 2010. This market segment is growing at a compound annual growth rate (CAGR) of 8.7%, and is forecast to reach sales of $29 billion by 2015.

In the R&D tools market, DNA sequencing is an emerging growth opportunity for nanotechnologies. This sector is valued at $63 million in 2010 and is expected to increase at a 37% compound annual growth rate (CAGR) to reach $305 million in 2015.

Mass production of non-reflective polymer surfaces (nanofabrication) yields more efficiency in solar energy

A key hurdle in realizing high-efficiency, cost-effective solar energy technology is the low efficiency of current power cells. In order to achieve maximum efficiency when converting solar power into electricity, ideally there is a need for solar panel that can absorb nearly every single photon of light across the entire spectrum of sunlight and irrespective of the sun's position in the sky.

One way to achieve suppression of sunlight's reflection over a broad spectral range is by using nanotextured surfaces that form a graded transition of the refractive index from air to the substrate. Researchers in Finland have now demonstrated a scalable, high-throughput fabrication method for such non-reflecting nanostructured surfaces.

The main advances of this work are in the field of nanofabrication. It was published in a recent paper in Advanced Materials ("Non-Reflecting Silicon and Polymer Surfaces by Plasma Etching and Replication").

The process involves a maskless deep reactive ion etching process that produces nanospikes on a silicon wafer. The process is known as black silicon process. The geometry of the nanospikes i.e. height, width and also the density can be controlled by changing the etching parameters. The main strength of the maskless method is its high throughput.

Different applications require different types of surfaces, and in this study the Finnish team shows that the densest arrays of nanospikes with slightly positively tapered sidewalls had the lowest optical reflectance, while pyramid-shaped nanospikes were ideal for use as templates for polymer replication. Polymer replication techniques are typically high-throughput and low-cost methods which make them very attractive.

In this research it has been shown that both hot-embossing and UV-embossing of polymer is possible with the PDMS stamp. The use of polymers instead of silicon would be useful in high-volume applications due to lower costs. Nanospike-structured polymeric and silicon surfaces are non-reflective and additionally they can be made ultrahydrophobic and self-cleaning, by coating them with a low-surface energy coating. These kinds of inexpensive, non-reflective and self-cleaning surfaces have many applications, for instance in sensors and solar cells.

Another important issue is the mechanical durability of the nanostructured surfaces. At the moment the nanostructured surfaces damage quite easily but the team is studying ways to make the surfaces more robust.

To do this, first, an elastomeric stamp is produced by casting a PDMS layer on top of the nanospike-structured silicon surface (the original nanospikes were fabricated on full silicon wafers using the black silicon process). The PDMS is thermally cured and peeled off. Then, the PDMS stamp can be used to replicate the original nanospike pattern into other polymers, such as PMMA.

Building 3D Batteries with Coated Nanowires

The researchers at Rice University recently managed to find a way to coat nanowires with PMMA (Poly(methyl methacrylate)) coating that provides good insulation from the counter electrode while still allowing ions to pass easily through.This minimized separation between two electrodes manages to make the battery much more efficient.

In a battery, there are two electrodes separated by a thick barrier. The main objective is to bring everything into close proximity so this electrochemistry becomes much more efficient.

To achieve this, researchers took the concept of 3D batteries and coated millions of nanowires to create the 3D structure from the bottom up. By increasing the height of the nanowires, the amount of energy stored is increased while keeping the lithium ion diffusion distance constant.

The whole process involves the growing of 10-micron-long nanowires through electrodisposition in the pores of an anoidized alumina template. Then PMMA is coated onto the nanowire array, resulting in an even casing from top to bottom. The result of this work is ultimately expected to be batteries for scalable microdevices that possess a greater surface area than thin-film batteries.

10 best inventions in 2010

http://hotnewshome.com/offbeat/10-best-inventions-of-2010.html

Water Pollution and Nanotechnology

Nanotechnology is being used to develop solutions to three very different problems in water quality.

One challenge is the removal of industrial water pollution, such as a cleaning solvent called TCE, from ground water. Nanoparticles can be used to convert the contaminating chemical through a chemical reaction to make it harmless. Studies have shown that this method can be used successfully to reach contaminates dispersed in underground ponds and at much lower cost than methods which require pumping the water out of the ground for treatment.

Another challenge is the removal of salt or metals from water. A deionization method using electrodes composed of nano-sized fibers shows promise for reducing the cost and energy requirements of turning salt water into drinking water.

The third problem concerns the fact that standard filters do not work on virus cells. A filter only a few nanometers in diameter is currently being developed that should be capable of removing virus cells from water.

 

See the following for more about the potential of nanotechnology in removing contaminates from water.

 

Nanotechnology Applications in Water Pollution

 

1. Combining a nanomembrane with solar power to reduce the cost of desalinating seawater

2. Using iron nanoparticles to clean up carbon tetrachloride pollution in ground water

3. Using silver chloride nanowires as a photocatalysis to decompose organic molecules in polluted water.

4. Using an electrified filter composed of silver nanowires, carbon nanotubes and cotton to kill bacteria in water.

5. Nanoparticles that can absorb radioactive particles polluting ground-water

6. Coating iron nanoparticles allow them to neutralize dense, hydrophobic solvents polluting ground-water

7. Using nanowire mats to absorb oil spills

8. Using iron oxide nanoparticles to clean arsenic from water wells.

9. Using gold tipped carbon nanotubes to trap oil drops polluting water.

10. Using antimicrobial nanofibers and activated carbon in a disposable filter as an inexpensive way to clean contaminated water.

11. Researchers at Pacific Northwestern Laboratory have developed a material to remove mercury from groundwater. The material is called SAMMS, which is short for Self-Assembled Monolayers on Mesoporous Supports. This translates taking a ceramic particle whose surface has many nano-size pores and lining the nanopores with molecules that have sulfur atoms on one end, leaving a hole in the center that is lined with sulfur atoms as shown in figure-SAMMS. They line the nanopores with molecules containing sulfur because it bonds to mercury, so mercury atoms bond to the sulfur and are trapped in the nanopores.